Transaxle ground strap - is this really the only engine ground?

[Sodo]

My Smallcar Subaru conversion had ONLY a ground at the end of the transaxle.
Does a WBX have a ground from the engine to the body?
It should.

It seems really poor design to rely on a ground that crosses about 5 or 6 transaxle housings.

(photo copied from an unrelated Samba thread showing a corroded transaxle)

Here's a perfect example where starter current may choose the internal steel transaxle shafts and bearings over the corroded housing junctures.

Cuz if those connections corrode, each subsequent resistance is additive. Consequently the current will pass thru the nice shiny gearbox shafts and bearings.

And everyone knows what happens to bearings when you arc electricity across them, right?

It causes pits on the bearing surfaces.
On the races, and on the rollers.
Then the bearings don't last as long.
And they start to shed metal into the oil, and things get worse, contamination compounds.

Seems like a good idea to add a ground from the starter to the body.
And another from the alternator to the body.
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'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[dhaavers]

[kamzcab86]

[Ahwahnee]

Mine is in place in the origial location but I replaced the tired bradied cable with a black ground cable.

[mikemtnbike]

May be a placebo effect, but my van has seemed to run much more smoothly since adding an alternator to body ground several months ago. I did the starter to body ground several months before that with no noticeable changes.
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1991 Vanagon GL 2.1 AT Westfauxlia. "Frankie" Totaled https://www.thesamba.com/vw/forum/viewtopic.php?t=764510&highlight=carnage
1995 Eurovan Camper "Marzivan"
2020 GTI SE manual

[Sodo]

OK so ensure your ground from the cylinder head to the body is in good order.

Add a nice fat ground from your starter to the van for the high-current draw of the starter.

Perhaps another from the alternator to the van, appx equal size wire as the hot 12v+ wire. For the case where battery is low, and the alternator is putting out max current. This would proaly e redundant to the ground on the cylinder head (but a shorther path)

Thinking about possible assaults to the Vanagon transaxle lifetime, I started to wonder about that forward ground strap. On an OLD van, the transaxle lives in a pretty bad environment, covered with salt and humidity, water splashing, etc. There's appx 5 or 6 connections.

-engine to bellhousing (definitely corrosion here!)
-bellhousing to trans case
-trans case to gear garrier
-(syncro gear carrier to low-gear housing)
-to nose cone
-to ground strap.

This suggests you should actually DELETE the front transaxle ground, protecting the transaxle from ever becoming a ground path. There is no need for it. Resistance adding up on an old van in the 5 or 6 consecutive housing connections poses a risk to current choosing your precious, shiny, clean transaxle bearings as a ground path.

========== OK simplified ========

The proposal (for an old van) is to delete the forward ground to eliminate risk of current passing thru the transaxle bearings, and add a similarly sized ground at the starter. Anyone have comments on this idea?
_________________


'90 Westy EJ25, 2Peloquins, 3knobs, pressure-oiled GT mainshaft, filtered, cooled gearbox
'87 Tintop w 47k 53k, '12 SmallCar EJ25, cooled filtered gearbox
....KTMs, GasGas, SPOT mtb

[crazyvwvanman]

You really shouldn't add any ground wire that isn't heavy enough to carry starter cranking current all by itself. One day that might be the only engine/trans ground and it needs to up to safely doing the job it could face if the other grounds failed or were left unhooked.

Mark

[Sodo]

[Ahwahnee]

[dobryan]

Plenty of old air cooled VW busses and bugs had accel cables acting as grounds.
_________________
Dave O
'87 Westy w/ 2002 Subaru EJ25 and Peloquin TBD

"To travel hopefully is a better thing than to arrive." Robert Louis Stevenson

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[crazyvwvanman]

It is the metal things that somehow join the engine/tranny to the body that will try to act as grounds if no better ground path exists. Those brown ground wires are attached to the body so they are not in that category per se.

Mark

[mikemtnbike]

[Sodo]

[crazyvwvanman]

I was talking specifically about the idea of adding more grounds between the engine/trans and body as well as between the alternator case and body, not about grounds in general.

The starter uses its metal case contact with the engine/trans to carry ALL of the starting amps back to the battery negative post, through the ground straps that connect the engine/trans to the body (and then through the negative cable from the body to the battery negative post). If you add another such ground make sure they can each carry the full starting current in the event that they become the only such starting ground.

The alternator works the same way, using its metal case to carry ALL of the charging amp to the negative side of the battery(s) going through the engine/tranny to body ground straps.

I've seen various vans that had poor ground contact between the alternator case and alternator bracket and/or poor contact between the bracket and the engine case. This poor metal to metal contact causes a voltage drop in the charging circuit. The suggestion to add a ground between the alternator and body is one way to help this but it is better to add that wire between the alternator case and the engine case if that is where the problem is. Then fix or supplement the grounds between the engine case and the body but make sure they can each carry the starting current in the event that they become the only such starting ground some time in the future.

Mark

[DanHoug]

[danfromsyr]

2G ground from starter to chassis
4G wire from Alt case to that same starter GND on the starter side not the chassis side
10G wire from coil housing to the Chassis side of the 2G Starter Gnd wire

clean and inspect the chassis gnds seasonally as well as battery terminals.

note that a dull grey terminal is lead oxide and has less conductivity than a shiny and sealed terminal connection.
seal with your choice of smear or spray on snake oils.
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[Sodo]

[crazyvwvanman]

Yes, the lower starter mounting stud is the place I use for an extra ground strap. There are some nearby open holes in the lip of the frame rail where diesel engine mounting bars would otherwise go. M8 bolt holes, scrape the paint off, attach pre-made FLAPS ground cable, usually black coated. If too long I coil the new cable around a screwdriver handle first to take up any excess length in the new #4 cable.

I have been called on to help countless people with their charging systems and aux battery charging issues. I measure the ground voltage drop on the alternator case as a matter of course. Not that often a big problem but sometimes. It needs to be checked under load, like with high beams on and dash fan on speed 2.

Mark

[danfromsyr]

maybe we should start a discussion on 'sacrificial anodes' for our transaxles in extreme environments.
california and arizona need not worry.
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[Sodo]